使用磷酸法於農林生物質之水解前處理

Hydrolysis Pretreatment of Agroforestry Biomass by Using Phosphoric Acid Method

郭冠圻(Kuan-Chi Kuo)

指導教授 ： 蔡文田

國立屏東科技大學/農學院/木材科學與設計系所/碩士(2009年)

https://doi.org/10.6346/NPUST.2009.00299

摘要

在過去，生質燃油的生產所使用的原料，例如大豆、玉米、以及甘蔗，這些可能會造成糧食競爭之作物，因此造就第二代生質作物-使用農業與林業廢棄物作為生質能源的來源。酸水解在生質酒精製程中，是一重要的前處理步驟，其會影響六碳糖與五碳糖的產率，以及影響後續發酵所生產的酒精品質。一般所使用的酸可分為濃酸與稀酸水解兩種方式，例如硫酸（H2SO4）與鹽酸（HCl），但傳統的酸水解方式可能會引起木質纖維素被碳化或產生一些化學物質，而該化學物質可能會抑制後續的發酵過程。相較於這些傳統的酸液，利用磷酸（H3PO4）進行水解，可以避免這些問題產生。本研究選定五種農林廢棄物（即稻稈、桂竹、狼尾草、蔗渣、玉米穗軸）作為試樣原料，在於其纖維素含量（53～65 ％）高。這些料原之化學及熱化學特性測定結果如下：碳 > 40 wt ％，低熱值（LHV）> 15.9 MJ/kg，以及灰分值< 10 wt ％。另一方面，木糖含量作為磷酸水解之各項條件程序（包含粒徑、固液比、浸漬時間、溫度）的一項重要指標。前處理實驗結果發現，在生質廢棄物磷酸水解中最重要的因子為浸漬時間，可以觀察到木糖的含量會隨著浸漬時間增加而增加，另一個重要參數為粒徑大小，也會造成對水解的明顯效果。本研究初步發現，以磷酸為農林廢棄物前處理之藥劑是一合適的水解程序，將會對其接續產生酒精的發酵程序扮演一相當重要影響的角色。

關鍵字

酸水解 ； 磷酸 ； 木質纖維素 ； 木糖

並列摘要

In the past, raw materials used in the production of biofuels were crops such as soybean, corn and sugarcane. However, it may put in competition with grain crops. It thus promotes the second generation biomass products using agricultural and forestry wastes as energy sources. Acid hydrolysis is an important pretreatment step in the bioethanol production processes. The yields of six-carbon and five-carbon sugars are dependent on process conditions, which will affect the alcohol production quality in the subsequent fermentation. The common used acid hydrolysis can be divided into two methods by concentrated and dilute acids such as sulfuric acid (H2SO4) and hydrochloric acid (HCl). It should be noted that the typical used acids are liable to cause the carbonization of lignocellulose and to produce some chemical substances that may inhibit the fermentation process. By contrast with these typical acids, the hydrolysis with phosphoric acid (H3PO4) can prevent these problems occurring. In this study, five agroforestry wastes（i.e., rice straw, makino bamboo, napiergrass, bagasse, and corn cob）were selected as raw materials due to their high cellulose contents (53～65 ％). Based on the chemical and thermal properties of these raw precursors thus determined, the main properties are given as follows: C > 40 wt ％, low heating value (LHV) > 15.9 MJ/kg, and Ash content < 10 wt ％. On the other hand, the xylose content was analyzed as an efficiency indicator for H3PO4-hydrolysis under various process parameters (including particle size, solid-liquid ratio, soaking time and temperature). Based on the results in the pretreatment experiment, the most important parameter in the acid hydrolysis of biomass wastes with H3PO4 was found to be the soaking time. The xylose yield was observed to increase at higher soaking time. The particle size is another important variable, which had a significant effect on the hydrolysis. This preliminary study showed that the pretreatment of agroforestry wastes with H3PO4 was suitable for acid hydrolysis which played a vital role in the subsequent fermentation for producing bioethanol.

並列關鍵字

Acid hydrolysis ； Phosphoric acid ； Lignocellulose ； Xylose

參考文獻

蔡易霖（2008）感應加熱技術熱解纖維料狼尾草之研究。國立屏東科技大學木材科學與設計系碩士論文。第34～38頁。

陳文恆、郭家倫、黃文松、王嘉寶（2007）纖維酒精技術之發展。農業生技產業季刊9：63～69。

林俊義（2006）能源作物之國外推動經驗與國內發展展望(下) ，行政院農業委員會農業試驗所技術服務季刊17（1）：5～10。

林曉洪、吳錦泉、蔡易霖（2007）鉀鹽處理桂竹製造粉狀活性碳之研究。中華林學季刊40(1)：81～95。

王松永（1993）木材之燃燒熱值與其影響因數探討。 林產工業 12（2）：35~45。